1. The Field of the Invention
The present invention relates to a method and apparatus for removing dust entrained in an air stream and, in particular, to a method and apparatus utilizing a unique cyclonic air flow, coupled with an improved filter assembly, to remove substantially all particles from the air stream while achieving long filter life, great savings in space and reduced capital and maintenance costs.
2. The Prior Art
The present invention is a dust collector of the type which can most advantageously be used with devices which use air flows to remove dust and debris from product, such as the deduster devices described in my U.S. Pat. Nos. 4,299,693 and 4,631,124, the disclosures of which are incorporated herein by reference. My earlier devices employ gravity to feed the dust and impurity laden particulate material through a linear kinetic energy cell, which cell generates an electric field to neutralize the static electrical charges, which is what causes the dust to adhere to the particulate material. With the static charge neutralized, the dust can be separated by an air flow substantially transverse to the path of the flow of particulate material. This cleaning or separation can be accomplished by using a pressurized air stream or a vacuum. However, this process, while cleaning the product, results in the creation of a volume of air heavily laden with dust an debris, much of which is extremely small in size. However, it should be noted that the present invention is a stand alone device completely separate from the dedusters covered by the above mentioned U.S. Pat. Nos. 4,299,693 and 4,631,124.
The present invention provides means to collect dust and debris from an air stream, regardless of the source of the dust and debris, and to remove that dust and debris from the carrier air. Thus only substantially clean air will be released into the environment and the dust and debris previously entrained therein will collected for proper disposal or recycling.
A traditional dust collector would be difficult to locate indoors when large air volumes are to be handled. As an example, in order to clean a dusty 5,000 cu ft. stream of air, a traditional dust collector would require at least 1,000 sq. ft. of cloth filter surface and a housing approximately 6 ft. sq. and 20 ft tall. In comparison, the housing for a cyclonic dust filter according to the present invention would be approximately 3 ft sq. by 6 ft tall, depending on the style of dust discharge.
The traditional dust collector contains at least 120 filter bags which need to be serviced periodically. This task requires approximately two days of work for a crew of three, in other words, about forty eight work hours, during which time the dust collector is in a down conditionIn comparison, the subject cyclonic dust filter has a single cartridge which can be changed by a single worker in about five minutes.
Development of reverse pulse dust collectors, which use periodic reverse air pulses to clean filters, has stabilized in recent years with the use of filter bags and, more recently, with cartridge style filter units. Due to their compact size, the cartridge style filter has become very attractive to plant operators. Its ease of installation and the large filtering area provided by the filter cartridges have presented strong incentives for their use. By utilization of standard reverse pulse hardware, the filter cleaning operation of filter cartridges becomes somewhat similar to that of cloth bag filters. Unfortunately, in multi cartridge dust collectors, the reverse pulse air velocity is considerably lower requiring a reduced air to cloth ratio, usually less than 2:1